Add locations to error reporting.

code/compiler/13/error.cpp

@@ -3,3 +3,26 @@
 const char* type_error::what() const noexcept {
     return "an error occured while checking the types of the program";
 }
+
+void type_error::pretty_print(std::ostream& to, parse_driver& drv) {
+    to << "encountered error while typechecking program: ";
+    to << description << std::endl;
+
+    if(loc) {
+        to << "occuring on line " << loc->begin.line << ":" << std::endl;
+        to << std::endl << "```" << std::endl;
+        drv.print_highlighted_location(to, *loc);
+        to << "```" << std::endl;
+    }
+}
+
+void unification_error::pretty_print(std::ostream& to, parse_driver& drv, type_mgr& mgr) {
+    type_error::pretty_print(to, drv);
+    to << "the expected type was:" << std::endl;
+    to << "  \033[34m";
+    left->print(mgr, to);
+    to << std::endl << "\033[0mwhile the actual type was:" << std::endl;
+    to << "  \033[32m";
+    right->print(mgr, to);
+    to << "\033[0m" << std::endl;
+}

code/compiler/13/error.hpp

@@ -1,21 +1,30 @@
 #pragma once
 #include <exception>
+#include <optional>
 #include "type.hpp"
+#include "location.hh"
+#include "parse_driver.hpp"
+
+using maybe_location = std::optional<yy::location>;
 
 struct type_error : std::exception {
     std::string description;
+    std::optional<yy::location> loc;
 
-    type_error(std::string d)
-        : description(std::move(d)) {}
+    type_error(std::string d, maybe_location l = std::nullopt)
+        : description(std::move(d)), loc(std::move(l)) {}
 
     const char* what() const noexcept override;
+    void pretty_print(std::ostream& to, parse_driver& drv);
 };
 
 struct unification_error : public type_error {
     type_ptr left;
     type_ptr right;
 
-    unification_error(type_ptr l, type_ptr r)
+    unification_error(type_ptr l, type_ptr r, maybe_location loc = std::nullopt)
         : left(std::move(l)), right(std::move(r)), 
-            type_error("failed to unify types") {}
+            type_error("failed to unify types", std::move(loc)) {}
+
+    void pretty_print(std::ostream& to, parse_driver& drv, type_mgr& mgr);
 };

code/compiler/13/main.cpp

@@ -144,8 +144,9 @@ int main(int argc, char** argv) {
         std::cout << def_defn.second->name;
         for(auto& param : def_defn.second->params) std::cout << " " << param;
         std::cout << ":" << std::endl;
-
         def_defn.second->body->print(1, std::cout);
+
+        std::cout << std::endl;
     }
     try {
         typecheck_program(driver.global_defs, mgr, env);
@@ -153,14 +154,8 @@ int main(int argc, char** argv) {
         scope.compile();
         gen_llvm(scope);
     } catch(unification_error& err) {
-        std::cout << "failed to unify types: " << std::endl;
-        std::cout << "  (1) \033[34m";
-        err.left->print(mgr, std::cout);
-        std::cout << "\033[0m" << std::endl;
-        std::cout << "  (2) \033[32m";
-        err.right->print(mgr, std::cout);
-        std::cout << "\033[0m" << std::endl;
+        err.pretty_print(std::cout, driver, mgr);
     } catch(type_error& err) {
-        std::cout << "failed to type check program: " << err.description << std::endl;
+        err.pretty_print(std::cout, driver);
     }
 }